Conventionally, magnet-molding is known as a method of fixing a permanent magnet to an iron core of a laminated rotor core used for a motor. In this method, the iron core having the permanent magnet inside a magnet insertion portion (magnet insertion hole) is heated to a certain temperature, and thereafter molding resin is injected into the magnet insertion portion and is heated and cured. That is how the permanent magnet is fixed to the iron core.
In this method, however, the resin cured after the injection remains attached to a surface of the iron core, and thus a process for removing such residual resin is required, which is a factor preventing reduction in lead time.
In view of the above, for example, Patent Document 1 discloses a method in which a metallic dummy plate 91 is placed on a surface (on a resin injection side) of an iron core 90, and molding resin (hereinafter simply referred to as resin) 93 is injected from a gate (small injection hole) 92 formed in the dummy plate 91 (see FIG. 13). In this method, the resin 93 cured after the injection remains attached not to the surface of the iron core 90 but to a surface of the dummy plate 91. Thus, by detaching the dummy plate 91 from the surface of the iron core 90, the residual resin can be removed together. Therefore, compared to the conventional method, lead time can be significantly reduced.
In the figure, a numeral 94 shows a permanent magnet. A numeral 95 shows a magnet insertion portion. Numerals 96, 97 show an upper die and a lower die for holding the iron core 90, respectively. A numeral 98 shows a resin reservoir pot. A numeral 99 shows a plunger for injecting the resin 93 from the resin reservoir pot 98 into the magnet insertion portion 95.